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It takes about 20 minutes after we eat before our stomachs feel full. That's one reason why it's important to see how much food we're really eating.
By Brian Wansink, Ph.D.
msnbc.com contributor
updated 5/4/2007 9:30:15 AM ET 2007-05-04T13:30:15

Your stomach can't count calories.

It can’t count the number of spoonfuls of Golden Grahams cereal you had for breakfast. It can’t count the number of ounces in the overpriced Frappuccino you drank on the way to work. It can’t count the number of french fries you inhaled in the first 90 seconds of your lunch break. It doesn't know how many scoops of the aptly named Chubby Hubby ice cream (a whopping 330 calories per half-cup) you ate standing in the front of the refrigerator when you got home.

Our stomachs just aren't designed to keep accurate track of how much we have eaten. If we could really see all that we're putting in our mouths, we'd probably eat a lot less.

Despite the cliché, our eyes are typically not bigger than our stomachs. In fact, our eyes are often better at telling us how much to eat than our bellies.That's because it takes about 20 minutes after we eat before our stomach starts registering that we're full. 

If you could look back and see all of the handfuls of potato chips you've already gobbled before shoveling in another, you'd likely hestitate before reaching back into the bag.

But we're hungry!
We can't count on our memories to help us, either. Take the popular but diet-destroying all-you-can-eat buffet.

In a study published this month in the journal Perceptual and Motor Skills, my colleague Dr. Collin Payne and I promised a free chicken wing buffet to 52 graduate students (17 men and 35 women) while they watched the Super Bowl at a sports bar in Urbana, Ill. As part of the study, the waitresses were instructed to clear the dishes at only half of the tables.

If people had their tables continually cleared, they continually ate. Clean plate, clean table, get more, eat more. Their stomachs didn't keep track of how much they'd eaten, so the students kept on eating until they thought they were full. Each of these people ate an average of seven chicken wings apiece.

The students who did not have their table bused were less of a threat to the chicken population. After the game was over, they had eaten an average of two fewer chicken wings per person — that's 28 percent less than those whose tables had been bused.

The chicken-wing gobblers didn't believe they were influenced by a clean table — they simply didn't remember chowing down as much as they did. They claimed they ate so much because they were hungry. That's the big danger of not having visual cues.

Seeing is believing
Do yourself a favor — make sure you see the food before you eat and while you eat it.

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We find that when people put everything on their plate before they start eating — including, snacks, dinner or dessert — they eat about 14 percent less than when they take smaller amounts and go back for seconds or thirds.

Instead of eating directly out of a package or box, put your snack in a separate dish and leave the box in the kitchen. You will be less likely to eat more and more ... and more. 

Whether you are eating chicken wings or cookies, you’ll eat less if you see what you’ve already eaten.

The same is true for beverages — it’s easy to forget how much soda you’ve guzzled if there’s nothing to remind you. So keep your eye on the empties.

For that matter, if you want to keep friends from overimbibing at your next dinner party, keep the empty wine bottles on the table and pour refills into fresh glasses without clearing the others.

Not only will you spend less party time cleaning up, seeing the evidence of how much they've drunk could help your friends get home more safely.

Brian Wansink, Ph.D., author of "Mindless Eating — Why We Eat More Than We Think," is director of the Cornell Food and Brand Lab.

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